Because of the impact caused by infection with the human immunodeficiency virus (HIV-1), considerable effort is being directed at induction of protective immune responses against this virus. Most cases of HIV-1 infection are acquired through sexual contact, which involves virus entry via mucosal tissues. Since mucosal tissues are protected by immune responses which function with a significant degree of independence from the systemic immune system, protective mucosal immune responses against HIV-1 require direct targeting of the mucosal immune system. Most of the previous immunization strategies against HIV-1 have been directed at the generation of humoral responses to the envelope protein following systemic immunization, since this is the main target of the humoral response after natural infection. However, these strategies have proven problematic due to the extensive sequence variability present in this protein. In this research proposal we intend to assess both mucosal humoral and cellular immune responses in mice after mucosal immunization with HIV-1 non- envelope proteins (e.g., reverse transcriptase (RT) and gag proteins), which are essential viral proteins with a significant degree of conservation among various HIV-1 isolates. We will focus on the generation of antigen-specific cytotoxic T-lymphocytes, since they are able to recognize and attack virus-infected cells, against which humoral responses may not be effective. Initially, mice will be immunized with recombinant HIV-1 RT delivered to mucosal inductive sites in the presence of various mucosal adjuvants/delivery systems. RT-specific antibodies (secretory IgA, serum IgA, serum IgG) will be measured in nasal washes, small intestinal secretions and serum from immunized mice by antigen- specific ELISA. The presence of cell-mediated immune responses in cells from the spleen and various mucosal compartments (Peyer's patches, mesenteric lymph nodes, small intestinal intraepithelial compartment, small intestinal lamina propria) will be determined as follows: 1) In- vitro proliferative assays 3/H thymidine incorporation); 2) Chromium release assays for the determination of antigen-specific cytotoxic T- lymphocytes (CD4-, CD8-); 3) ELISPOT assays for the determination of cells producing individual cytokines (Type 1 [INF-gamma] and Type 2 [IL4, IL5] responses). The information gained from this research will prove useful in understanding the induction of immune responses after mucosal immunization, and will provide basic information that will be useful for vaccine design against HIV in humans.